When I first got Anki, I likely did mess around and make a deck called “science”, though that doesn’t show on my deck list so I assumed I deleted it. When I tried making a deck called “science” earlier (I was going to add different lessons and thought to organise my Anki), it didn’t appear.
The “science+” in the screenshot is from naming the deck something else on creation and only afterwards trying to change it to “science”.
I tried uploading my current data to Anki Web (just in case it was somehow using old data) but it still adds a plus. I apologise if it’s an easy fix.